Combined autotrophic nitritation and bioelectrochemical-sulfur denitrification for treatment of ammonium rich wastewater with low C/N ratio.

A novel combined autotrophic nitritation and bioelectrochemical-sulfur denitrification (CANBSD) process was developed for treatment of synthetic ammonium-rich wastewater with low carbon/nitrogen ratio. Total nitrogen removal of the CANBSD was higher than 95 %, the effluent SO4 (2-) was lower than 1280 mg L(-1), and the maximum nitrogen volumetric loading rate was 1.2 kg m(-3) day(-1) when (1) the influent NH4 (+)-N was lower than 1008 mg L(-1), (2) hydraulic retention time was between 3.7 and 32 h, (3) the DO was between 0.5 and 1.2 mg L(-1), (4) the pH was between 7.5 and 8.2, and (5) the temperature was between 28 and 30 °C. Both the NH4 (+)-N removal and conversion to NO2 (-)-N in the nitritation membrane reactor (NMBR) were maintained at about 50 %, and the residual NH4 (+)-N and accumulated NO2 (-)-N were subsequently treated in the bioelectrochemical-sulfur three-dimensional denitrification reactor. The CANBSD energy consumption was 0.13 and 3.4 kWh m(-3), respectively, for influent NH4 (+)-N of 100 and 1000 mg L(-1). The energy consumption of CANBSD was close to that of partial nitritation-ANNMMOX.